In a conference room, one large-size shared display device may be shared among client devices held by multiple users, respectively. In this situation, a participant in a distant place can also display an image on the shared display device using an online conferencing system. The shared display device displays an image sent from a client device of a user as a presenter. After completion of a presentation of the first presenter, the shared display device displays an image sent from a client device of the next presenter. At this time, images to be displayed on the shared display device need to be switched in association with the change in presenter.
Patent Document 1 teaches that images being respectively displayed on multiple computers are displayed on a shared display concurrently in a window format. Patent Document 2 discloses a video conferencing system including a video switching mechanism for use in a group conference among multiple terminal devices connected to a multipoint control unit (MCU). This document teaches that the MCU analyzes audio streams to decide on a speaker high in priority in order to forward a video stream of the speaker to all participants.
Patent Document 3 teaches that information sources are switched according to the direction of a display without any selection operation. This document teaches that information sources to be displayed on a display are switched depending on the angle of a stand of a display device. Non-Patent Document 1 teaches a solution to sharing a screen among multiple clients using a display installed in a conference room. This document teaches that the screen is switched by clicking on the screen of a client and a content is shared.    [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-149440    [Patent Document 2] Published Japanese Translation of PCT application No. 2005-516557    [Patent Document 3] Japanese Patent Application Laid-Open No. H05-232910    [Non-Patent Document 1] “Intel Unite Solution User Guide v3.15,” [online], Intel, [searched on May 18, 2017], the Internet <URL: http://download.intel.com/support/software/applications/unite/sb/intel_unite_user_guide.pdf>